charger: fix up the charge_get_percent default return value
charger: fix up the charge_get_percent default return value

The charge_get_percent should return zero when the HW design doesn't
include a battery(ie. no CONFIG_BATTERY). The reason is that the
function handle_new_power_state in usb_tc_drp_acc_trysrc_sm.c will
check the battery status (via pd_is_battery_capable) to determine
whether the device needs to issue DPM_REQUEST_HARD_RESET_SEND or not.
If we return 100, the pd_is_battery_capable() will return true and
that makes the PD do the HARD_RESET and cause the device to reboot
endlessly.

BUG=b:242949656
BRANCH=None
TEST=make buildall
     flash the ec.bin to the device and check the typec pd is working

Signed-off-by: Zhuohao Lee <916bf7ddbf0565669e59e3cb2b613381a48066c0@chromium.org>
Change-Id: I59d24c4f58bed3538b70eeba5eff11566bd5f455
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3891810
Reviewed-by: Diana Z <cb2016afc7183e5356c690dc63b4ba817470501a@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec